Comedians could find themselves on the wrong side of the law under the SNP's proposed hate crime Bill, campaigners have warned.

If passed, the Hate Crime and Public Order (Scotland) Bill will make "abusive language" that is "likely to stir up hatred" a criminal offence.

But a broad coalition uniting secularists and Christians warns that comedians at the celebrated Edinburgh Fringe could end up in trouble with the law if they make offensive jokes.

Simon Calvert, a spokesman for the Free to Disagree campaign and head of public affairs at The Christian Institute, said the Bill has "huge implications" for comedy in Scotland.

He fears even legitimate speech will be caught up in the new law. 

"Under the hate crime plans 'abusive' – that is rude and insulting – words and behaviour considered 'likely' to stir up hatred against certain groups could be prosecuted as a 'stirring up' offence," he said.

"If a comedian at the Edinburgh Fringe made controversial comments about age, disability, religion or transgenderism and were reported by a disgruntled audience member, they could find themselves under investigation by the police.

"Even if their comments didn't meet the threshold for an offence, officers would still be required to investigate the matter, using up valuable police resources.

"The proposed legislation could chill free speech and artistic expression in Scotland. What comedian in their right mind would want to perform at the Fringe if their jokes could land them in hot water? It's no laughing matter."

Comedians Rowan Atkinson and Elaine C Smith have both criticised the law, as has the Catholic Church in Scotland.

Catholic bishops have warned that anyone expressing biblical values could be deemed to have committed a crime.

They have called on the SNP to ensure that any new law protects freedom of religion and expression.

"A new offence of possessing inflammatory material could even render material such as the Bible and the Catechism of the Catholic Church...inflammatory," said Anthony Horan, Director of the Catholic Parliamentary Office. 

"The Catholic Church's understanding of the human person, including the belief that sex and gender are not fluid and changeable, could fall foul of the new law.

"Allowing for respectful debate, means avoiding censorship and accepting the divergent views and multitude of arguments inhabiting society."

The Free Church of Scotland said the Bill in its current form will have a "significant detrimental effect on free speech within our society".

Concerns have also been raised that the law risks turning officers into thought police.

Calum Steele, General Secretary of the Scottish Police Federation said: "We are firmly of the view this proposed legislation would see officers policing speech and would devastate the legitimacy of the police in the eyes of the public. That can never be an acceptable outcome – and we should never forget that the police in Scotland police only with the consent of the people.

"Police officers are all too aware that there are individuals in society who believe that to feel insulted or offended is a police matter. The Bill would move even further from policing and criminalising of deeds and acts to the potential policing of what people think or feel, as well as the criminalisation of what is said in private."

Mr Steele added: "If the Bill as presented is passed, those accused of the new offences of stirring up hatred will not have the opportunity to prove that they did not intend to stir up hatred or that they had no reason to suspect their conduct would do so.

"We do not for one second suggest that prejudice, racism or discrimination are desirable qualities in our society but the need to address those matters when they reach a criminal level is met by laws already in place and the cost to free speech of going further with this Bill is too high a price to pay for very little gain."